Two simple donor-acceptor multifunctional pure organic light-emitting molecules[(9H-carbazol-9-yl)(4-hydroxyphenyl)-methanone(CzMP)and(4-hydroxyphenyl)(10H-phenothiazin-10-yl)methanone(PTZMP)]with distinct aggregation...Two simple donor-acceptor multifunctional pure organic light-emitting molecules[(9H-carbazol-9-yl)(4-hydroxyphenyl)-methanone(CzMP)and(4-hydroxyphenyl)(10H-phenothiazin-10-yl)methanone(PTZMP)]with distinct aggregation-induced emission(AIE)properties were synthesized.Surprisingly,CzMP showed a long room temperature phosphorescence lifetime(>900 ms),and PTZMP exhibited triple emission of prompt fluorescence(PF),room temperature phosphorescence(RTP)and thermally activated delayed fluorescence(TADF).Furthermore,CzMP effectively responded to mechanical external forces and solvent fumigation,exhibiting dual-mode mechanochromic luminescence(MCL)including multiple fluorescence color shifts and phosphorescence switching.Time-dependent density functional theory(TDDFT)calculations were investigated to explain different luminescence properties of the two molecules,and the single crystal of CzMP was obtained and analyzed to demonstrate the unique molecular stacking pattern and strong intermolecular interactions in close association with phosphorescence emission.The multifunctional luminescent properties of the emitters explored in this work could be more effectively applied to a wide range of applications,such as information encryption and anti-counterfeiting.展开更多
Aggregation-induced thermally activated delayed fluorescence(TADF)phenomena have attracted extensive attention recently.In this paper,several theoretical models including monomer,dimer,and complex are used for the exp...Aggregation-induced thermally activated delayed fluorescence(TADF)phenomena have attracted extensive attention recently.In this paper,several theoretical models including monomer,dimer,and complex are used for the explanation of the luminescent properties of(R)-5-(9H-carbazol-9-yl)-2-(1,2,3,4-tetrahydronaphthalen-1-yl)isoindoline-1,3-dione((R)-ImNCz),which was recently reported[Chemical Engineering Journal 418129167(2021)].The polarizable continuum model(PCM)and the combined quantum mechanics and molecular mechanics(QM/MM)method are adopted in simulation of the property of the molecule in the gas phase,solvated in acetonitrile and in aggregation states.It is found that large spin–orbit coupling(SOC)constants and a smaller energy gap between the first singlet excited state and the first triplet excited state(△E_(st))in prism-like single crystals(SC_(p)-form)are responsible for the TADF of(R)-lmNCz,while no TADF is found in block-like single crystals(SC_(b)-form)with a larger △E_(st).The multiple ultralong phosphorescence(UOP)peaks in the spectrum are of complex origins,and they are related not only to ImNCz but also to a minor amount of impurities(ImNBd)in the crystal prepared in the laboratory.The dimer has similar phosphorescence emission wavelengths to the(R)-lmNCz-SC_(p) monomers.The complex composed of(R)-lmNCz and(R)-lmNBd contributes to the phosphorescent emission peak at about 600 nm,and the phosphorescent emission peak at about 650 nm is generated by(R)-lmNBd.This indicates that the impurity could also contribute to emission in molecular crystals.The present calculations clarify the relationship between the molecular aggregation and the light-emitting properties of the TADF emitters and will therefore be helpful for the design of potentially more useful TADF emitters.展开更多
文摘传统联邦学习训练模型时假定所有参与方可信,但实际场景存在恶意参与方或恶意攻击模型,现有的联邦学习算法面对投毒攻击时,存在模型性能严重下降的问题。针对模型投毒问题,本文提出一种基于联邦平均(federated averaging,Fedavg)与异常检测的联邦检测算法——FedavgCof,该算法考虑到所有参与方之间的差异对比,在中心服务器和本地模型之间添加异常检测层,通过基于聚类的本地异常检测因子(cluster-based local outlier factor,COF)异常检测算法剔除影响模型性能的异常参数,提升模型鲁棒性。实验结果表明,虽然新型投毒方式攻击性更强,但是FedavgCof能够有效防御投毒攻击,降低模型性能损失,提高模型抗投毒攻击能力,相较于Median和模型清洗算法平均提升精度达到10%以上,大幅提升了模型的安全性。
文摘Two simple donor-acceptor multifunctional pure organic light-emitting molecules[(9H-carbazol-9-yl)(4-hydroxyphenyl)-methanone(CzMP)and(4-hydroxyphenyl)(10H-phenothiazin-10-yl)methanone(PTZMP)]with distinct aggregation-induced emission(AIE)properties were synthesized.Surprisingly,CzMP showed a long room temperature phosphorescence lifetime(>900 ms),and PTZMP exhibited triple emission of prompt fluorescence(PF),room temperature phosphorescence(RTP)and thermally activated delayed fluorescence(TADF).Furthermore,CzMP effectively responded to mechanical external forces and solvent fumigation,exhibiting dual-mode mechanochromic luminescence(MCL)including multiple fluorescence color shifts and phosphorescence switching.Time-dependent density functional theory(TDDFT)calculations were investigated to explain different luminescence properties of the two molecules,and the single crystal of CzMP was obtained and analyzed to demonstrate the unique molecular stacking pattern and strong intermolecular interactions in close association with phosphorescence emission.The multifunctional luminescent properties of the emitters explored in this work could be more effectively applied to a wide range of applications,such as information encryption and anti-counterfeiting.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11974216,11874242,21933002 and 11904210)Shandong Provincial Natural Science Foundation,China(Grant No.ZR2019MA056)+1 种基金the support of the Taishan Scholar Project of Shandong Provincethe project funded by China Postdoctoral Science Foundation(Grant No.2018M642689)。
文摘Aggregation-induced thermally activated delayed fluorescence(TADF)phenomena have attracted extensive attention recently.In this paper,several theoretical models including monomer,dimer,and complex are used for the explanation of the luminescent properties of(R)-5-(9H-carbazol-9-yl)-2-(1,2,3,4-tetrahydronaphthalen-1-yl)isoindoline-1,3-dione((R)-ImNCz),which was recently reported[Chemical Engineering Journal 418129167(2021)].The polarizable continuum model(PCM)and the combined quantum mechanics and molecular mechanics(QM/MM)method are adopted in simulation of the property of the molecule in the gas phase,solvated in acetonitrile and in aggregation states.It is found that large spin–orbit coupling(SOC)constants and a smaller energy gap between the first singlet excited state and the first triplet excited state(△E_(st))in prism-like single crystals(SC_(p)-form)are responsible for the TADF of(R)-lmNCz,while no TADF is found in block-like single crystals(SC_(b)-form)with a larger △E_(st).The multiple ultralong phosphorescence(UOP)peaks in the spectrum are of complex origins,and they are related not only to ImNCz but also to a minor amount of impurities(ImNBd)in the crystal prepared in the laboratory.The dimer has similar phosphorescence emission wavelengths to the(R)-lmNCz-SC_(p) monomers.The complex composed of(R)-lmNCz and(R)-lmNBd contributes to the phosphorescent emission peak at about 600 nm,and the phosphorescent emission peak at about 650 nm is generated by(R)-lmNBd.This indicates that the impurity could also contribute to emission in molecular crystals.The present calculations clarify the relationship between the molecular aggregation and the light-emitting properties of the TADF emitters and will therefore be helpful for the design of potentially more useful TADF emitters.
